Method of reducing magnetic and/or oxidic contaminants in lithium metal oxygen compounds

Abstract

A method of reducing magnetic and/or oxidic contaminants in lithium metal oxygen compounds in particle form, in order to obtain purified lithium metal oxygen compounds, by means of treatment in a grinding process and sifting process with continuous or non-continuous removal and obtaining of the purified lithium metal oxygen compound. The grinding process and sifting process are terminated prematurely before the residue amounts to less than 1% of the quantity m. The residue, containing contaminants, is discarded.

The invention claimed is: 
     
       1. A method of reducing magnetic and/or oxidic contaminants in doped and non-doped lithium metal oxygen compounds in particle form, comprising the steps of:
 a) providing a lithium metal oxygen compound in particle form in a quantity m, said particulate lithium metal oxygen compound containing contaminants; 
 b) introducing a portion of from 5 to 15% of the quantity m of the lithium metal oxygen compound into a grinding chamber; 
 c) grinding the lithium metal oxygen compound; 
 d) sifting the ground lithium metal oxygen compound to obtain a purified lithium metal oxygen compound and a residue of non-converted lithium metal oxygen compound containing the contaminants; 
 e) removing the purified lithium metal oxygen compound obtained by grinding c) and sifting d); 
 f) discarding the residue obtained in d); and 
 g) repeating steps b) to e) until the whole quantity m has been converted and the residue amounts to 3% to 0.01% of the quantity m. 
 
     
     
       2. The method according to  claim 1 , wherein the particles of the lithium metal oxygen compound in part a) have a carbon-containing coating at least in parts. 
     
     
       3. The method according to  claim 1  wherein the lithium metal oxygen compound is doped with B, Al, Mg, Ca, Sr, P, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Zn, Sn, Nb, Mo, Ru, or W, or mixtures thereof. 
     
     
       4. The method according to  claim 3 , wherein the lithium metal oxygen compound has an empirical formula with Li x , with 0<x and 0<y selected from Li x MO 2 , Li x M 2 O 4 , Li x M 5 O 12 , Li x M y O 4 , Li x M 2 O 4 , Li x M 2 O 3 , Li x M 3 O 4 , Li 2 MO 3 , Li x M 2 O 3 , Li x M 3 O 4 , LiMO 2 , LiM′ 0.5 M″ 0.5 O 2 , or wherein the lithium metal oxygen compound has an empirical formula with Li 1+x  with 0<x and 0<y selected from Li 1+x M 2−x O 4 , Li 1+x M 2 O 4 , Li 2 MO 3 , Li 1+x M′ 2−x M″ x (PO 4 ) 3 , or wherein the lithium metal oxygen compound has an empirical formula Li 1−x  with 0<x and 0<y selected from Li 1−x M′ y M″ 2−y O 4 , Li 1−x M′ 1.5 M″ 0.5 O 4 , or Li 1−x M′ y M″ 1−y O 2 , wherein M is a transition metal, M′ is one or more metals selected from the group consisting of B, Al, Na, Mg, Ca, Sr, P, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Ga, In, Y, Zr, Nb, Mo, Ru, and W, M″ is one or more metals selected from the group B, Al, Na, Mg, Ca, Sr, P, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Ga, In, Y, Zr, Nb, Mo, Ru, and W, and M′″ is one or more metals selected from the group consisting of B, Al, Na, Mg, Ca, Sr, P, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Ga, In Y, Zr, Nb, Mo, Ru, and W. 
     
     
       5. The method according to  claim 1 , wherein in step b) the introduction of the lithium metal oxygen compound is terminated after introducing a portion of 10% of the quantity m. 
     
     
       6. The method according to  claim 1 , wherein the purified lithium metal oxygen compound is continuously removed and obtained during the grinding and sifting. 
     
     
       7. The method according to  claim 6 , wherein the lithium metal oxygen compound is subjected to a grinding process and sifting process until the residue has been reduced to a portion of from 2% to 0.5% of the quantity m. 
     
     
       8. The method according to  claim 1 , wherein the grinding process and the sifting process are terminated when the residue amounts to 2% to 0.5% of the quantity m. 
     
     
       9. The method according to  claim 1 , wherein the purified lithium metal oxygen compound obtained by grinding c) and sifting d) is removed until the residue amounts to 1% of the quantity m. 
     
     
       10. The method according to  claim 1 , wherein the grinding and sifting of the lithium metal oxygen compound is carried out in a single device. 
     
     
       11. The method according to  claim 1 , wherein the grinding and sifting of the lithium metal oxygen compound is carried out in separate devices. 
     
     
       12. The method according to  claim 1 , wherein the method according to steps a) to e) also comprises a further grinding step. 
     
     
       13. The method according to  claim 12 , wherein the further grinding step takes place in a further device separate from the grinding and/or sifting device. 
     
     
       14. The method according to  claim 12 , wherein the grinding and/or sifting and the further grinding step takes place in a single device.